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<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <script>
        // 简单数据类型传参
        function fn(a) {
            a++;
            console.log(a); // 11
        }
        var x = 10;
        fn(x);
        console.log(x); // 10
    </script>
</body>

</html>